牛伝染性リンパ腫（EBL）は，牛伝染性リンパ腫ウイルス（BLV）による感染症で，国際的に重要な家畜疾病である。日本では届出伝染病に指定されており，経済的被害は甚大である。EBLの主な特徴として，感染牛の多くは無症状だが，約30%は持続性リンパ球増多症（PL）を呈し，数%は発症する。感染伝播様式には，水平感染と垂直感染の2つがある。近年，日本での感染率は急増しており，特に若齢牛での発症が問題となっている。

清浄化対策においては，2006年から2008年に農林水産省の委託を受け高感度定量PCR法が開発された。この手法により，ウイルス量を指標とした「高度感染牛摘発型」の清浄化対策が可能となった。さらに，JRA畜産振興事業の支援を受け，清浄化のための，①高度感染牛の摘発と分離飼育モデル，②感染子牛育成センター設置モデル，③地域BLV検査センターと感染子牛育成センターを併用した総合型清浄化モデル，の開発研究が段階的に実施された。

今後の清浄化対策の課題としては，垂直感染，特に感染母牛から生まれる感染子牛対策が挙げられる。また，地域全体での協調的な取り組みの必要性や，清浄化対策の持続可能性を担保するためのコスト負担の問題も重要である。これらの課題の解決が，EBL清浄化に向けた次のステップとなるであろう。

Bovine leukemia virus (BLV), a retrovirus, infects B cells of ruminants and is integrated into the host genome as a provirus for lifelong infection. After a long latent period, 1% to 5% of BLV-infected cattle develop aggressive lymphoma, enzootic bovine leukosis (EBL). Since the clonal expansion of BLV-infected cells is essential for the development of EBL, the clonality of proviral integration sites could be a molecular marker for diagnosis and early prediction of EBL. Recently, we developed Rapid Amplification of the Integration Site without Interference by Genomic DNA Contamination (RAISING) and an analysis software of clonality value (CLOVA) to analyze the clonality of transgene-integrated cells. RAISING-CLOVA is capable of assessing the risk of adult T-cell leukemia/lymphoma development in human T-cell leukemia virus-I-infected individuals through the clonality analysis of proviral integration sites. Thus, we herein examined the performance of RAISING-CLOVA for the clonality analysis of BLV-infected cells and conducted a comprehensive clonality analysis by RAISING-CLOVA in EBL and non-EBL cattle. RAISING-CLOVA targeting BLV was a highly accurate and reproducible method for measuring the clonality value. The comprehensive clonality analysis successfully distinguished EBL from non-EBL specimens with high sensitivity and specificity. A longitudinal clonality analysis in BLV-infected sheep, an experimental model of lymphoma, also confirmed the effectiveness of RAISING-CLOVA for early detection of EBL development. Therefore, RAISING-CLOVA is a reliable technology for monitoring the clonality of BLV-infected cells and would contribute to reduce the economic losses by EBL development.

地方病性（成牛型）牛伝染性リンパ腫は牛伝染性リンパ腫ウイルス（Bovine leukemia virus : BLV）の感染が原因であり，牛リンパ腫のほとんどを占めている。感染牛の数%は数か月から数年の無症状期を経て，B細胞性のリンパ腫である地方病性牛伝染性リンパ腫（Enzootic bovine leukemia : EBL）を発症する。EBLを発症すると，効果的な治療はなく予後不良となり死亡する。現在のところ，BLVの感染やEBLの発症を予防する効果的なワクチンは無く，EBLの発症を防ぐためには，衛生対策の徹底によりBLVの感染を阻止するしかない。BLVの清浄化対策を進めるには，牛毎の感染の有無，および感染度合いを把握して分離飼育や淘汰の優先順位を把握する必要がある。これらの把握には血液検査が必須となり，農家に一定の経費を強いることとなる。

宮城県におけるEBLの届け出数は，平成14年の4頭から始まり令和5年では176頭と増加の一途をたどっている。家畜共済における宮城県内のEBLによる死廃頭数は，令和5年度で137頭となり，共済金評価額の合計は約1億円であった。このうち，農場でEBLと診断された牛が42頭，屠場でEBLとして検出され枝肉全部廃棄となった牛が95頭であり，屠場で検出された牛の方が多い。

宮城県では以前より家畜保健衛生所等および宮城県農業共済組合が試験的にBLVの清浄化対策を行ってきた。しかし，これらの対策を実施した農場は宮城県全体の養牛農場数に比べればほんの一部でしかなく，検査費用も無料もしくは一部補助であったために継続できたものと考えられる。

宮城県全体でEBLの発生を減少させるためには，BLVに感染した牛を減らす事が重要であり，県全域でのBLV清浄化対策が必要となってくる。しかし，現在までの試験的清浄化対策とは異なり，宮城県全域で実施するためには，農家負担が必須であり，補助等を含め何らかの対策を講じる必要がある。

令和6年7月に宮城県，全農宮城県本部および宮城県農業共済組合で「宮城県における牛伝染性リンパ腫に係るワーキンググループ」を発足した。今後現実的なBLV対策の実施について協議していく予定である。

After bovine leukemia virus (BLV) enters the lymphocytes of the infected host, the viral RNA reverse transcribes into viral DNA and the DNA integrates into the host chromosomal genome to establish infection. The viral DNA integrated into the host genome is called the provirus, and its copy number is called the proviral load. The proviral load of BLV-infected cattle is proportional to the risk of viral transmission to cohabitating cattle. Based on our previous research, we categorize BLV-infected cattle with a proviral load greater than 2000 copies/ 50 ng of genomic DNA as “very high risk”, 500 copies or more as “high risk”, 500 copies or less as “low risk”, and 100 copies or less as “very low risk”. In addition to that, we have proposed the following measures to control BLV on farms: (1) keeping high risk cattle separate from uninfected cattle, (2) not using equipment contaminated with body fluids or blood, and (3) reducing breeding with high risk cattle as much as possible. The most unique feature of our proposed control measures is that it is acceptable for low risk and uninfected cattle to be housed in the same pen. This manuscript introduces our studies that provide the evidence for this control measure and examples of farms where the BLV control have been applied.

反芻獣ペスチウイルス（RPV）は牛ウイルス性下痢ウイルス（BVDV）およびボーダー病ウイルス（BDV）に代表される反芻獣を宿主とするウイルスである。豚がRPVに感染すると豚熱ウイルス（CSFV）の血清学的診断に影響を及ぼす恐れがあるため，2018年の豚熱国内発生前の検体を用いて茨城県の牛および豚におけるRPV感染状況を調査した。豚飼養農場226戸中4戸（1.8%）が抗体検出ELISA陽性であり，個体レベルでの抗体陽性率は0.25%（12/4,881）であった。これら4戸の豚における中和試験では，3戸がBVDV1中和抗体陽性であり，牛と豚飼養農場の混在地域に立地又は牛飼養農場に隣接していた。また，1戸はBDV中和抗体陽性であり，過去にBDVが分離された農場であった。牛飼養農場377戸中20戸（5.3%）から44頭の持続感染（PI）牛が摘発され，PI牛の75%からBVDV1bが検出された。RPV抗体陽性豚飼養農場4戸のうちの1戸はPI牛摘発農場と隣接していた。以上から，抗体検出ELISA陽性となった豚飼養農場の感染源の一つとして，乳用牛群のPI牛が示唆された。反芻動物におけるRPV感染状況の把握および豚におけるRPV感染の予防は，CSFV感染豚の迅速かつ正確な診断に役立つ。さらに，豚からRPV抗体が検出された場合，CSFVとRPVに対するウイルス中和試験による抗体識別が重要である。

The economic impact of Highly Pathogenic Avian Influenza (HPAI) in the U.S. is explored, focusing on events from 2014-2015 and from 2022 onward. The 2014-2015 outbreak affected over 7 million turkeys and 43 million egg-laying hens and pullets, resulting in $879 million government expenditures. The 2022 outbreak has been more widespread and long-lasting, affecting over 100 million birds across multiple states, but formal economic assessments are still ongoing. Export restrictions due to HPAI significantly influenced market dynamics, causing price fluctuations. As of 2024, HPAI continues to pose challenges, with emerging infections in dairy cattle, although they exhibit mild symptoms. For future analysis of the economic impact of HPAI in the U.S., the rational behavior of economic agents and factors other than HPAI should be considered, and vaccination, along with thorough surveillance, might also be worth including in the analysis.

In recent years, outbreaks of animal infectious and zoonotic diseases have occurred frequently, and the importance of epidemiology, animal health economics, and One Health has been recognized. Furthermore, with the digitalization of society and the emergence of artificial intelligence, the need for quantitative evidence is expanding to every corner of society. In order for epidemiology to be implemented in society as the response, it is essential to improve the educational system.

From December 2023 to February 2024, to understand the current state of epidemiological education at the undergraduate level at Japanese veterinary schools and to form a network of veterinary epidemiologists in these universities, the Epidemiology Section of the Japanese Society of Veterinary Sciences conducted a questionnaire survey at all 17 universities across Japan. In addition, in 2023, an email-based survey on undergraduate education was conducted with the epidemiologists from a total of 10 veterinary schools: one in North America, one in South America, two in Southeast Asia, one in Australia, one in sub-Saharan Africa, and four in Europe. The information was compiled and examined.

Of the 17 veterinary schools in Japan, 11 are public universities, and 8 of these were conducting joint epidemiology education with 2 schools each (4 pairs). Therefore, a total of 13 educational courses including all 17 universities responded, and the response rate was 100%. Twelve out of 13 courses (92.3%) offered independent epidemiology lectures, and all schools offered epidemiology lectures. The average number of faculty members teaching epidemiology per university was 2.1, with a median of 1 and a maximum of 7. The mean and median numbers of epidemiology lectures in a course was 13.2 and 14, with a minimum of 5 and a maximum of 15. Only 58.8% (10/17) of the 17 universities were conducting practical training and exercises related to veterinary epidemiology. Of the 5 educational courses including 7 universities that do not incorporate practical training, all of them cited lack of time in their curriculum as the reason, 2 universities (1 response) said they did not have enough teachers, and 1 university did not have enough computers. Three of them (2 responses) described that they would like to incorporate practical training if there was a useful practical textbook in an open question.

On the other hand, all 10 overseas universities offer epidemiology training/seminar courses, and of these, 9 schools offer the course as a practical course, with the exception of one university on the African continent where it is held as part of a lecture course. Practical subjects teaching epidemiology varied, including epidemiology training and clinical subjects, with some universities used the data provided from the government and others delving into infectious disease mathematical model simulations and genomic phylogenetic tree analysis.